ImmunoGen Inc. abruptly canceled a mid-stage study of its drug to treat small-cell lung cancer Tuesday, driving the Waltham biotechnology company’s shares down nearly 19 percent.
The move came after an independent data-monitoring panel concluded ImmunoGen’s experimental drug — given in a clinical trial to some patients in combination with two existing medicines — had resulted in more infections and infection-related deaths than the same treatments given to another group of patients who were not taking the ImmunoGen drug.
“They weren’t seeing enough efficacy to continue the study in light of the high level of toxicity,” said ImmunoGen’s chief executive, Daniel Junius.
It was the third serious setback in recent weeks for a Massachusetts biotechnology company. Ariad Pharmaceuticals Inc. of Cambridge stopped selling its approved leukemia drug after the Food and Drug Administration warned it could cause life-threatening blood clots. And Vertex Pharmaceuticals Inc., which is scheduled to move from Cambridge to Boston next month, cut 370 jobs, including 175 in Massachusetts, due to a sharp decline in sales of its hepatitis C drug.
The end of ImmunoGen’s trial raised questions about its drug development program. The company had used the same targeting-and-binding technology successfully with a Genentech breast cancer drug called Kadcyla that won FDA approval in February.
The technology, which deploys a proprietary cancer-killing agent and a “linker” that binds to a chemotherapy drug, is also used in at least eight other drug candidates in ImmunoGen’s pipeline — some developed by the company and others by its partners.
But the small-cell lung cancer drug program was among the most advanced.
That doubt about the company’s technology prompted investors to sell Immunogen shares Tuesday. The stock fell $3.41, or nearly 19 percent, to $13.41.
Discontinuation of the drug trial “eviscerates their pipeline in the near term,” Joel D. Sendek, an analyst with the investment bank Stifel Nicolaus & Co. in New York, wrote in a note to investors. “Immunogen’s early stage pipeline looks unappealing to us at this time.”
Immunogen, however, seemed undeterred. The company disclosed Tuesday that it has begun clinical development of a drug to treat ovarian, endometrial, and other cancers.
That effort joins two other ImmunoGen clinical development programs for experimental drugs to treat non-Hodgkin’s lymphoma and lung, head, and neck cancers.
The company is also working with the French drug maker Sanofi SA, which owns Genzyme in Cambridge, on another experimental treatment for non-Hodgkin’s lymphoma.
“I won’t deny that it’s a disappointment,” Junius said of the small-cell lung cancer trial, suggesting that ImmunoGen would have to study data from the trial before determining how to proceed with its lung cancer drug program.
“But we still feel very good about our technology,” he said. “This is not going to slow anything down in terms of the other compounds we’re pursuing. In the larger picture, it’s a bump in the road rather than something more significant.”Robert Weisman
can be reached at email@example.com. Follow him on Twitter @GlobeRobW.